So I purchased a 99 Sea Doo spx about a month ago. Took it out for the first time and experienced bad cavatation at all speeds just bouncing off rev limiter. Took it home inspected the impeller and wear ring. Impeller was bent and dinged up so I ordered a new impeller, wear ring, bearings, seals, nose cone, carbon ring, float ring, Bellow the whole 9 yards rebuild the pump. Ran great the first 2 times zero cavatation took right off. 3rd time out today since rebuild it slowly started acting up, at top speed it would keep cutting out randomly and now it is back to cavitatating but only holeshot. I car barley get on plane it just bouncing off limiter, but once I'm on plane and I gun it it takes off fine. So the issue only happens off plane. Ran it on the trailer to watch carbon ring, which is new but that was the first thing I could think of, no leaks everything fine. Any help would be appreciated thanks!
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Help with new to me spx 800
- Thread starter Tlr386
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Well, you need to go thru the entire fuel system and rebuild the carb with genuine Mikuni rebuild kits and buy new needle and seats too. Replace any gray fuel lines and the fuel/water separator strainer. You'll need about 25" of 5/16" fuel line and about 22ish clamps stainless steel. Also not a bad Idea to get a new fuel selector switch, they're pricey for the 5/16 lines but I would only buy OEM. Get the part# and look on ebay and prey on someones misfortunes that's dumping new parts on the cheap.
Look up in the pump tunnel, make sure there isn't any weeds or crap to disturb the water intake. Also, when you had the pump off, did you replace or install a new neoprene seal to seal the pump to the hull? If not that is a source of cavitation for sure. In the second pic you can see where I also seal the pump shoe to the hull, its Permatex Ultra black rtv.
Look up in the pump tunnel, make sure there isn't any weeds or crap to disturb the water intake. Also, when you had the pump off, did you replace or install a new neoprene seal to seal the pump to the hull? If not that is a source of cavitation for sure. In the second pic you can see where I also seal the pump shoe to the hull, its Permatex Ultra black rtv.
Okay I guess the pump is coming back out. Also I've been doing some reading and it seems the driveshaft bumpers are very important to keep the splines in the correct place I did notice mine was not attached to the driveshaft and pretty chewed up I'm wondering if this could be my issue as well. Hopefully they are not stripping out.
Alright so I took her back out today after rebuilding the carbs, changing fuel lines, neoprene seal on jet pump, new driveshaft and bumpers. It worked perfect for about 5 minutes then back to cavitatating out of the hole. Once I'm on plane it takes off then cavatates randomly. I'm all out of ideas here I don't know what else I can replace
funsummerahead
Active Member
Intake grate, loose, cracked, broken, falling off? At the bottom of the lake?
funsummerahead
Active Member
Ride plate secure? If not use some good silicone and Loctite to make sure it doesn't loosen up.
funsummerahead
Active Member
Maybe the splines are stripping on your engine pto… I've seen that a couple times.
funsummerahead
Active Member
OK then you need to be more specific on your "cavitating" issue. It shouldn't be cavitating as all the drive line parts are nice, tight and new. What about the jet pump wear ring? Is that new? I didn't see that in your other posts.
Yes it is. I even rode it around today with the seat off because the only thing I can think is the carbon ring which is new but maybe I got a bad one or something not sure but there's no leaks around that area at any rpm. IDK how to be any more specific. I pin the throttle off idle and it just revs of the limiter and barley moves. Eventually it will get on plane if I keep the throttle pinned while banging the limiter for 2 straight minutes. Once it hits plane it takes off then it will "lose traction again" then go it's like driving a high hp car with bald tires in the rain it just spins spins finally gets traction then looses it again.
funsummerahead
Active Member
The carbon ring just keeps water from leaking into the hull and has ABSOLUTELY nothing to do with cavitation. You should use spell check because it's hard to understand what you're trying to tell us. So it revs up to very high rpm's and doesn't move? And then it gets going and then keeps revving and slows down?
funsummerahead
Active Member
Simply put - if the ski / engine is reving high and not going you have a problem in the driveline...
Such as the -
PTO from the engine,
Driveshaft
Impeller
Jet pump wear ring
Intake grate
Ride plate
That's about all it can be if you're describing this correctly...
Such as the -
PTO from the engine,
Driveshaft
Impeller
Jet pump wear ring
Intake grate
Ride plate
That's about all it can be if you're describing this correctly...
The carbon seal has everything to do with cavitation. I don't see a problem with his spelling either?
Lift up on the front of the engine and then the two rear sides to see if you have a failed engine mount.
Lift up on the front of the engine and then the two rear sides to see if you have a failed engine mount.
funsummerahead
Active Member
The carbon seal keeps water out of the hull and that's about it. It has NOTHING to do with cavitation at all. How would the carbon seal on the driveshaft cause cavitation????
SPELLING? WHAT DOES THIS EXACTLY MEAN???
I pin the throttle off idle and it just revs of the limiter and barley moves. Eventually it will get on plane if I keep the throttle pinned while banging the limiter for 2 straight minutes
barley moves is I think barely moves. Fine but what does
"banging the limiter for 2 straight minutes" exactly mean?
He has a problem in the driveline..
I've replaced plenty of carbon seals that failed on skis that were taking on water without any cavitation.
I would love to know how a carbon seal could cause cavitation as it's on the INSIDE of the hull???
SPELLING? WHAT DOES THIS EXACTLY MEAN???
I pin the throttle off idle and it just revs of the limiter and barley moves. Eventually it will get on plane if I keep the throttle pinned while banging the limiter for 2 straight minutes
barley moves is I think barely moves. Fine but what does
"banging the limiter for 2 straight minutes" exactly mean?
He has a problem in the driveline..
I've replaced plenty of carbon seals that failed on skis that were taking on water without any cavitation.
I would love to know how a carbon seal could cause cavitation as it's on the INSIDE of the hull???
As soon as the carbon seal "breaks the seal" it will ingest air and immediately cavitate.
And banging on that limiter, lol that's typical car talk when the engine is stuttering on the rev limiter. Some guys say"bounce box", rev limiter, limiter, stutter box. It's all just slang or lingo
And banging on that limiter, lol that's typical car talk when the engine is stuttering on the rev limiter. Some guys say"bounce box", rev limiter, limiter, stutter box. It's all just slang or lingo
The carbon seal can allow air in.
Man I guess I'm the same kind of guy as the OP because I'm scratching my head here wondering what's wrong with that transmission. His message still seems right to me.
Man I guess I'm the same kind of guy as the OP because I'm scratching my head here wondering what's wrong with that transmission. His message still seems right to me.
funsummerahead
Active Member
So how does a carbon seal injest air when it IS UNDER THE WATER???
And WTF is "typical car talk" mean when referring to a Sea Doo PWC???
The pump is a low pressure area so when the carbon seal is bad it can actually suck air from the engine compartment into the pump tunnel causing cavitation. It’s sucking air from the engine compartment instead of water through the pump.
It’s a real thing and they don’t always leak water into the hull like you would think.
I think the OP is being pretty clear. He hits the throttle and the engine goes to full rpm but the ski isn’t moving just like a car with a slipping clutch of you just held the throttle to the floor.
It can only be one thing if your driveshaft, PTO and impeller splines aren’t slipping. You pump is pumping air not water. It has to be pulling air through the pump instead of water so that leaves....
1. Carbon seal.
2. Intake grate and/or ride plate.
3. Pump to hull seal.
4. Wear ring.
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funsummerahead
Active Member
Yes I agree but the carbon ring or seal is new and has 2 new rubber O rings in it as well. He says many of the parts are BRAND NEW too. I would bet ONE American dollar that it's the PTO on the engine. I only know what I've seen myself. It sounds like you know a lot more about this situation than I do but I just can't see the carbon ring going bad and creating this problem, especially when it's NEW. I would think that after putting in a lot of NEW parts and still having a problem it is most likely something that WASN'T replaced... And my 1 dollar is on the PTO from the engine.
GGuillot
Well-Known Member
It'll suck air if the carbon seal is failing, if you're not pulling water through the impeller efficiently it'll cavitate. Most noticable when it starts to go south is at the hole shot and with a passenger, I'm starting to get this on my 97' GTX here lately. Accompanying the cavitation, I'm noticing a little bit of water splashing in at the carbon seal area also, not a lot but some water getting in.
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